Vinyl chloride polymers plasticized with alkoxyethyl esters of (1&#39;, 2&#39;-dicarboxyethyl) octadecenoic acid



' Patented Sept. 25, 1951 UNITED STATES oFFicE VINYL CHLORIDE POLYMERSPLASTICIZED WITH ALKOXYETIIYL ESTERS OF (1',2'-

DICARBOXYETHYL)OCTADECENOIC ACID No Drawing. Application March 25, 1950,

Serial No. 151,995

6 Claims.

1 -This invention relates to compositions comprising polymers of vinylhalides and relates more particularly to compositions comprising vinylchloride polymers plasticized with alkoxy-ethyl esters oft1'2'-dicarboxyethyl)octadecenoic acid.

A wide variety of plasticizer has been employed for the purpose ofimproving the physical properties of vinyl chloride polymers. Particularattention has been given to the improvement of flexibility and heat andlight stability of such plasticized compositions. improvement inflexibility has been obtainable only by sacrificing other desirableproperties of an ideal polyvinyl chloride composition, such as lowvolatility, color and heat stability, water absorption, etc.

Now I have found that very good flexibility, without sacrifice oftemperature stability and low volatility, is imparted to vinyl chloridepolymers when there are employed with the polymers certain alkoxyethylesters of (1',2'-dicarboxyethyl) octadecenoic acid. Esters of this typeare disclosed in the Clocker patent, U. S. No. 2,188,888. Briefly, theyare obtainable by the addition reaction of maleic anhydride with oleicacid or its alkoxyethyl esters. While isomeric products are possible,and the position at which the anhydride residue is attached to the oleiccompound is not known, the reaction of oleic acid or an alkyl oleatewith maleic anhydride proceeds probably according to the scheme:cnucmncnzcmcnwcoon err-:0

n-c=0 CH3(CHQ)=CHCH=CH(CH2)is-zCOOR.

H-C=O 0 I CH2C==O wherein X is a whole number between 5 and 8 and R is amember of the group consisting of hydrogen and alkyl radicals of from 1to 6 carbon atoms.

Esterification of the resulting adduct with an wherein R is an alkylgroup of from 1 to 6 carbon' atoms, and R is a member of the groupconsisting In many instances the 2 of R and CzHiOR'. Mixed alkoxyalkylesters are thus obtainable.

Because of uncertainty concerning the position at which the maleicresidue is attached to the oleic group, the present esters will behereinafter referred to without stipulating the position of the(1',2'-dicarboxyethyl) group.

I have found that in order to obtain stable, light-colored adductscertain reaction conditions must be adhered to carefully. For example,while the addition of maleic anhydride to oleic acid takes place undervarying reaction conditions,

useful plasticizers for the present purpose are bestprepared byconducting the reaction for comparatively short periods of time, say,from 1 hour to 8 hours, at relatively low temperatures, i. e., attemperatures not exceeding the decomposition point of the initialreactants. I havefound also that great care should be used in isolatingthe desired products. After the esterification I preferably fractionatethe crude reaction mixture under a very low vacuum, i. e., at vacuums of1 mm. of mercury or less. Fractionation at such low pressures minimizesthe formation of dark colored impurities whose presence in the finishedproduct leads to poor plasticizing ability. Dark colored impurities arealso avoided by preparing the tris(alkoxyethyl)(1,2'-dicarboxyethyl)octadecenoates according to the procedure describedin my co-pending application, Serial No. 44,393, filed February 15,1950. p

The tris(alkoxyethyl) (1',2'-dicarboxyethyl)- octadecenoates arevaluable plasticizers for polyvinyl chloride and copolymers of at least'70 per cent by weight of vinyl chloride and up to 30 per cent by weightof an unsaturated monomer copolymerized therewith, for example vinylacetate, vinylidene chloride, etc. Adducts of acyclic olefinic acids andlong-chained unsaturated acids have been hitherto generally suggestedfor use as softening agents. I have now found, however, that thetris(alkoxyethyl) (l,2'-dicarboalkoxy)- octadecenoates in which thealkoxy radical has from 1 to 6 carbon atoms are of outstanding value asplasticizers, these esters serving not only to soften vinyl chloridepolymers, but also to impart simultaneously a high degree of lowtemperature flexibility, very good temperature stability and greatmechanical strength to these polymers. While many of the estersdescribed in the prior art are incompatible with polymers and copolymersof vinyl chloride, and do not give continuous. homogeneous compositions,esters of the present alkoxyethyl esters are compatible with vinylchloride polymers and show no exudation of plasticizer even atplasticizer content of up to 50 per cent. Although the quantity ofplasticizer will depend upon the particular polymer to be plasticizedand upon its molecular weight, it is generally found that compositionshaving from 5 per cent to 50 per cent by weight of plasticizer will, inmost cases, be satisfactory for general utility. The good flexibility ofthe plasticized compositions increases with increasing plasticizerconcentration.

In evaluating plasticizer efilciency use is made of the followingempirical testing procedures;

C0mpatibz'lity.-Visual inspection of the plasticized composition isemployed, incompatibility of the plasticizer with the polymer beingdemonstrated by cloudiness and exudation of the plasticizer.

Hardness.A standard instrument made by the Shore Instrument Company isused for this determination and expresses the hardness in units from 1to 100. The hardness of a composition is judged by its resistance to thepenetration of a standard needle applied to the composition under astandard load for a standard length of time.

Low temperature flexibiZity.-Low temperature flexibility is one of themost important properties of elastomeric vinyl compositions. While manyplasticizers will produce flexible compositions at room temperature theflexibility of these compositions at low temperatures may varyconsiderably, i. e., plasticized polyvinyl chloride compositions thatare flexible at room temperature often become very brittle and uselessat low temperatures. Low temperature flexibility tests herein employedare according to the Clash- Berg method. This method determines thetorsional flexibility of a plastic at various temperatures. Thetemperature at which the vinyl composition exhibits an arbitrarilyestablished minimum flexibility is defined as the low temperatureflexibility of the composition. This value may also be defined as thelower temperature limit of the plasticized compositions usefulness as anelastomer.

VoZatility.--Just as a decrease in low temperature often results indecreased flexibility of a plasticized polymer composition so does adecrease in plasticizer concentration when caused by volatilization ofthe plasticizer. Hence, plasticizers which are readily volatilized fromthe plasticized composition as a result of aging or heating areineificient because upon volatilization the plasticized compositionsbecome stiff and hard. The test for plasticizer volatility hereinemployed is that described by the American Society for Testing Materialsunder the designation D-744-44T.

Water resistance-The amount of water absorption and the amount ofleaching that takes place when the plasticized composition is immersedin distilled water for 24 hours is determined.

The invention is further illustrated, but not limited, by the followingexample:

Example 60 parts of polyvinyl chloride and 40 parts by weight of thetris(ethoxyethyl) ester of (1',2- dicarboxyethyl) octadecenoic acid aremixed on a rolling mill to a homogeneous blend. During the milling therewas observed substantially no fuming or discoloration. A molded sheet ofthe mixture was clear and transparent and substantially colorless.Testing of the molded sheet for low temperature flexibility, accordingto the testing procedure described above, gave a value of minus 46 C.which value denotes extremely good low temperature properties. Tests onthe volatility characteristics of the plasticized composition gave avalue of 2.21 per cent which shows very good retention of plasticizerand indicated good temperature characteristics of the composition. Theplasticized material had a hardness of 76 before the volatility test anda hardness of 76 after the volatility test. When subjected to heat at atemperature of 325 F. for a period of minutes the clarity and color ofthe molded product was substantially unchanged. Tests of thewater-resistance properties of the plasticized material employing thetest procedure described above showed a solids-loss of only 0.16 percent and an 0.50 per cent water absorption value.

Instead of the esters employed in the example above, other trisalkoxyethyl esters of (1',2- dicarboxyethyl) octadecenoic acid havingfrom 1 to 6 carbon atoms in the alkoxy group give similarly valuableplasticized polyvinyl chloride compositions. Thus, by employing 40 partsby weight of tris(methoxyethyl), tris(isobutoxyethy1) tris-(n-hexyloxyethyl) or tris(propoxyethyl) ester of(1',2'-dicarboxyethyl)octadecenoic acid with 60 parts by weight ofpolyvinyl chloride or with 60 parts by weight of a vinyl chloride-vinylacetate copolymer known to the trade as Vinylite, there are obtainedclear, colorless compositions of very good flexibility and stability.

While the above example shows only a composition in which the ratio ofplasticizer to polymer content is 40:60, this ratio being employed inorder to get comparable efficiencies, the content of ester to polyvinylchloride may be widely varied, depending upon the properties desired inthe final product. For manypurposes a plasticizer content of, say, fromonly 10 per cent to 20 per cent is preferred. The present esters arecompatible with polyvinyl chloride over a wide range of concentrations,up to 30 per cent of esters based on the total weight of the plasticizedcomposition yielding desirable products.

Although the invention has been described particularly with reference tothe use of the present tris(alkoxyethyl) esters of(1',2'-dicarboxyethyl) octadecenoic acid as plasticizers for polyvinylchloride, these esters are' advantageously employed also as plasticizersfor copolymers of vinyl chloride, for example, the copolymers of vinylchloride with vinyl acetate, vinylidene chloride, methyl methacrylate,acrylonitrile, etc. Preferably, such copolymers have a high vinylchloride content, i. e., a vinyl chloride content of at least 70 percent by weight of vinyl chloride and up to 30 per cent by weight of thecopolymerizable monomer.

The plasticized polyvinyl halide compositions of the present inventionhave good thermal stability; however, for many purposes it may beadvantageous to use known stabilizers in the plasticized compositions.Inasmuch as the present esters are substantially unreactive with thecommercially available heat and light stabilizers which are commonlyemployed with polyvinyl chloride or copolymers thereof, the presence ofsuch materials in the plasticized materials does not impair the valuableproperties of the present esters. The present esters are of generalutility in softening vinyl chloride polymers. They may be used as theonly plasticizing component in a compounded vinyl chloride polymer 1. Aresinous composition comprising a vinyl chloride polymer plasticizedwith a tris(alkoxyethyl) ester of (1',2'-dicarboxyethyl) octadecenoicacid in which the alkoxy group has from one to six carbon atoms.

2. A resinous composition comprising polyvinyl chloride plasticized witha tris-(alkoxyethyl) ester or (1',2'-dicarboxyethyl) octadecenoic acidin which the alkoxy group has from one to six carbon atoms.

3. A resinous composition comprising polyvinyl chloride plasticized witha tris- (alkoxyethyl) ester of (l',2'-dicarboxyethyl)octadecenoic acidin which the alkoxy group has from one to six carbon atoms, said esterbeing from iive to 50 per cent of the weight of the composition.

4. A resinous composition comprising a copolymer of at least 70 per centby weight 01' vinyl chloride and up to 30 per cent by weight of anunsaturated monomer copolymerizable therewith, said copolymer beingplasticized with a tris(alk oxyethyl) ester of (1'.2'-dicarboxyethyl)octadecenoic acid in which the alkoxy group has irom one to six carbonatoms.

5. A resinous composition comprising a copolymer of at least 70 per centby weight of vinyl chloride and up to 30 per cent by weight of anunsaturated monomer copolymerizable therewith, said copolymer beingplastlcized with a tris(alkoxyethyl) ester of (1'.2'-dicarboxyethyl)octadecenoic acid in which the alkoxy group has from one to six carbonatoms, and said ester being from five to 50 per cent of the weight ofthe composition.

6. A resinous composition comprising polyvinyl chloride plasticized withthe tris(ethoxyethyl) ester of (1',2'-dicarboxyethyl) octadecenoic acid,said ester being from five to 50 per cent of the weight 01' thecomposition.

J OACHIM DAZZI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Sarbach Oct. 24, 1944 Number

1. A RESINOUS COMPOSITION COMPRISING A VINYL CHLORIDE POLYMERPLASTICIZED WITH ATRIS(ALKOXYETHYL)ESTER OF (1'',2''-DICARBOXYETHYL)OCTADECENOIC ACID IN WHICH THE ALKOXY GROUP HAS FROM ONE TO SIX CARBONATOMS.